1. Bi-directional Integration, is a kind of integration testing process that combines top-down and bottom-up testing.
2. With an experience in delivering Bi-directional testing projects custom software development services provide the best quality of the deliverables right from the development of software process.
3. Bi-directional Integration testing is a vertical incremental testing strategy that tests the bottom layers and top layers and tests the integrated system in the computer software development process.
4. Using stubs, it tests the user interface in isolation as well as tests the very lowest level functions using drivers.
5. Bi-directional Integration testing combines bottom-up and top-down testing.
6. Bottom-up testing is a process where lower level modules are integrated and then tested.
7. This process is repeated until the component of the top of the hierarchy is analyzed. It helps custom software development services find bugs easily without any problems.
8. Top down testing is a process where the top integrated modules are tested and the procedure is continued till the end of the related module.
9. Top down testing helps developers find the missing branch link easily.

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Process of Bidirectional testing:

1. Bottom up testing starts from middle layer and goes upward to the top layer. For a very big system, bottom up approach starts at a subsystem level and goes upwards.
2. Top down testing starts from the middle layer and goes downward. For a very big system, top down approach, starts at subsystem level and goes downwards.
3. Big band approach is followed for middle layer. From this layer, bottom up approach goes upwards and top down approach goes downwards.

Advantages:

1. This approach is useful is useful for very large projects having several projects. When development follows a spiral model and module itself is as large as a system.
2. Both top down and bottom up approach starts at the start of the schedule.
3. It needs more resources and big teams for performing both, methods of testing at a time or one after the other.

Disadvantages:

1. It represents very high cost of testing as lot of testing is done.
2. It cannot be used for smaller systems with huge interdependence between different modules.
3. Different skill tests are required for testers at different level as modules are separate systems handling separate domains.